BOURBONNAIS -- After missing two weeks of training camp and being gone for a week for personal reasons, Chicago Bears middle linebacker Brian Urlacher has undergone arthroscopic surgery on his left knee.

An NFL source told the Tribune Urlacher underwent the procedure Tuesday, 26 days before the start of the regular season. The Bears and Urlacher have maintained all along that he will be ready to play against the Indianapolis Colts Sept. 9 at Soldier Field. It is unknown at this point if today's surgery will alter that timeline.

Urlacher was asked in an interview on Monday with WFLD Fox-32 if he had arthroscopic surgery during the time he was away from training camp at Olivet Nazarene University last week.

"No," Urlacher told Fox-32. "I am pretty sure if I got surgery we have to tell the NFL from what I understand, right? I definitely didn't get knee surgery. I was gone for personal reasons."

Fox host Lou Canellis then asked Urlacher if there was an arthroscopic surgery he could have and return in two weeks.

"I don't know," Urlacher said. "I am just going to keep resting right now. I have never had a scope. I don't know how that stuff works. This is the first time I have ever done anything to my knee so I am kind of new to this. I don't know. Honestly, I don't know how that works."

It's certainly possible Urlacher and the team decided later Monday that it was best for him to have the knee examined. He suffered a sprained MCL and PCL in the regular season finale Jan. 1 at the Metrodome. Urlacher was held out of the offseason program as he rehabilitated the knee and felt fine when training camp opened. But a week of wear and tear on the practice field led the knee to swell up and he was shut down. He last practiced July 31. Nick Roach has been playing middle linebacker in his place with Geno Hayes working with the first team at strong-side linebacker.

Urlacher did some running with a brace on Monday morning under the careful watch of the team's training staff while a walk-through was being conducted. The Bears expected he would likely miss some time in training camp but didn't expect a need to shut him down.

"I just think I did a lot of movements I hadn't done in a long time and being out there for 2 ½, three hours probably doesn't help, running around," Urlacher told Fox. "But it's practice. You gotta do it. I think just the shock of being out there so long and doing so many movements like that was too much for my knee.

"It is hard but there is a fine line between pushing it and easing into it, which is what I need to do. I just gotta get back out there for Sept. 9. Even if I just practice the week before, I'll be in good enough shape to make it through those games. But I gotta be out there when the games count."

Some players can return from arthroscopic knee surgeries quickly, within a matter of weeks. The source said the goal is for Urlacher to still be ready for the Colts game. Check back for more information throughout the day on this breaking story.